Process for preparing polymers

ABSTRACT

PROCESS FOR PREPARING A POLYMERIC MATERIAL WHICH COMPRISES POLYMERIZING ACRYLONITRILE OR ACRYLONITRILE ADMIXED WITH A MINOR AMOUNT OF AT LEAST ONE ETHYLENICALLY UNSATURATED COMPOUND COPOLYMERIZABLE THEREWITH IN THE PRESENCE OF A CATALYST SYSTEM CONSISTING OF REDOX TYPE CATALYST AND AT LEAST ONE OXIME IN AN AQUEOUS MEDIUM. THUS PRODUCED POLYMERS OR COPOLYMERS MAY BE USED AS STARTING MATERIALS FOR ACRYLIC SYNTHETIC FIBERS SUPERIOR IN BOTH WHITENESS AND HEAT STABILITY OF WHITENESS.

United States Patent @flice 3,810,878 PROCESS FOR PREPARING POLYMERS Hideo Sato and Kuuitoshi Shimizn, Fuji, Japan, assignors to Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan No Drawing. Filed Sept. 9, 1971, Ser. No. 179,227 Claims priority, application Japan, Sept. 22, 1970, 45/ 82,503 Int. Cl. (308i 1/62 US. Cl. 260-785 B 10 Claims ABSTRACT OF THE DISCLOSURE Process for preparing a polymeric material which comprises polymerizing acrylonitrile or acrylonitrile admixed with a minor amount of at least one ethylenically unsaturated compound copolymerizable therewith in the presence of a catalyst system consisting of redox type catalyst and at least one oxime in an aqueous medium. Thus produced polymers or copolymers may be used as starting materials for acrylic synthetic fibers superior in both whiteness and heat stability of whiteness.

This invention relates to a process for preparing polymeric materials. It more particularly refers to a new process for preparing polymers and copolymers of acrylonitrile.

There have been proposed many polymerization catalysts for preparing polymers and copolymers of acrylonitrile in an aqueous medium polymerization.

Such catalysts include substances which have ability to initiate polymerization by themselves such as persulfates and perborates, and redox type catalysts consisting of oxidizing agents which have no ability to initiate polymerization by themselves such as chlorates and potassium permanganate and reducing agents such as sulfoxy compounds. Generally the redox type polymerization catalyst is not a mere combination of any oxidizing and reducing substance but a unique combination of the two kinds of substances.

Usefulness of a polymerization catalyst depends on physical properties of the produced polymer as well as ability to initiate polymerization.

It is an object of this invention to provide a polymerization or copolymerization process of acrylonitrile in a novel catalyst system which has a high polymerizationinitiating ability and can produce polymers or copolymers having a desired degree of polymerization with high yields and being starting materials for acrylic synthetic fibers superior in both whiteness and heat stability of whiteness.

Other and additional objects of this invention will become apparent from a consideration of this entire specifiaction.

In accord with and fulfilling these objects, there is provided a process for preparing a polymeric material which comprises polymerizing (a) acrylonitrile or (b) acrylonitrile admixed with a minor amount of at least one ethylenically unsaturated compound copolymerizable therewith in an aqueous medium by using a catalyst system consisting of a redox type catalyst and at least one oxime of one of the two following general formulae:

1 HON=C and HON=6 R:

(I) (II) 3,810,878 Patented May 14, 1974 formaldoxime, ethyl-i-pentylketoxime, acetaldoxrme, ethyl-i-hexylketoxime, propmnaldoxime, ethyl-i-heptylketoxime,

n-butylaldoxime, i-butylaldoxime, n-pentylaldoxime,

ethyl-n-octylketoxime, ethyl-n-nonylketoxime, ethyl-2-methylbutyli-pentyl-aldoxime, 'ket-oxime, acetoxime, ethyl-3,3-dimethylpentylethylmethylketoxime, ketoxime,

i-butylmethylketoxime,

di-n-propylketoxime, methyl-n-pentylketoxime,

did-butylketoxime,

methylneopentylketoxime, n-hexylmethylketoxime, n-heptylmethylketoxime,

n-butyl-i-heptylketoxime, cyclohexanone oxime, cycloheptanone oxime,

n-decylmethylketoxime,

cyclooctanone oxime, diethylketoxime,

cyclodecanoue oxime and cycloundecanone oxime.

These oximes are preferably used in an amount of from about 5 to percent by weight based upon the total weight of the oxidizing agent and the amount of the oxime may be varied within the above-described range depending upon the polymerization conditions and the properties of the polymer.

The redox type catalyst according to the present invention comprises (1) at least one oxidizing substance and (2) at least one reducing sulfoxy compound.

Examples of suitable oxidizing substance include persulfuric acid, the water-soluble sodium, potassium, magnesium, ammonium salt thereof, hydroxylamine-N-monm sulfonic acid, the water-soluble sodium, potassium, magnesium, ammonium salt thereof, hydroxylamine-N,N-disulfonic acid, the water-soluble sodium, potassium, magnesium, ammonium salt thereof and sodium, potassium and ammonium chlorates.

Examples of suitable reducing sult'oxy compounds include sulfurous acid, water-soluble sodium, potassium, magnesium and ammonium sulfite, hyposulfite, bisulfite, and metabisulfite.

The amount of the oxidizing substance is usually about 0.1 to 10 percent by weight of the total weight of the acrylonitrile or the acrylonitrile admixed witha minor amount of the ethylenically unsaturated compound.

The amount of the reducing sulfoxy compound is usually up to 30 percent by weight of the total weight of the acrylonitrile or the acrylonitrile admixed with a minor amount of the ethylenically unsaturated compound.

Examples of suitable ethylenically unsaturated compounds copolymerizable with acrylonitrile include methacrylonitrile acrylic acid, u-chloroacrylic acid, a-bromoacrylic acid, methacrylic acid; acrylates such as methyl methacrylate, methoxy methacrylate, ethyl methacrylate, butyl methacrylate, or methyl acrylate, ethyl acrylate, butyl acrylate, methyl a-chloroacrylate, ethyl u-chloroacrylate, butyl a-chloroacrylate; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride; methacrylonitrile; acrylamide and methacrylarnide; m-chloroacrylamide or alkyl-substituted products thereof such as N,N dimethylacrylamide; methyl vinyl ketone; vinyl carboxylic acid and vinyl carboxylates such as vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl stearate; N-vinylimides, such as N-vinyl phthalimide, N-vinyl succinimide; methylene malonic acid ester, N-vinyl carbazole; vinyl furan; alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl sulfonic acids or salts thereof such as allyl sulfonic acid, methallyl sulfonic acid, p-styrene sulfonic acid, sodium, potassium and ammonium salts thereof; ethylene a,;8-dicarboxylic acids, anhydrides or derivatives thereof such as maleic acid, maleic anhydride, dimethyl maloate; vinylpyridines such as 2- vinylpyridine, 4 vinylpyridine, 2-methyl-5-vinylpyridine; l vinylimidazoles and alkyl-substituted l-vinylimidazoles, such as 2-, 4-, or S-methyl-l-vinylimidazole, and other C=C containing polymerizable materials. These compounds may be effectively used either alone or in various combinations of two or more selected monomers.

These ethylenically unsaturated compounds are employed in an amount of from 0.01 to 40 mole percent, preferably from 0.01 to 15 mole percent based on the acrylonitrile.

Known polymerization regulators may also be employed. Exemplary polymerization regulators include mercaptans such as dodecyl mercaptan and thioglycol. The amount of the polymerization regulators may preferably be from about 0.05 to 4 percent by weight of the total weight of the acrylonitrile or the acrylonitrile admixed with a minor amount of the ethylenically unsaturated compound.

Furthermore, there may be employed various compounds such as dyes, pigments, other coloring agents, stabilizers, surfactants and other additives which may be used in the production of acrylonitrile polymers and copolymers.

The present polymerization is effected in an aqueous medium and the monomeric material and water may be employed at a weight ratio of about 1:1 to 1:30. When the weight of water is less than that of the monomeric material it is difficult to control the polymerization such as degree of polymerization, distribution of degree of polymerization. On the other hand when water is too much, the concentration of the monomeric material becomes low and the polymerization is remarkably retarded for practical commercial purposes.

The polymerization is carried out in an acidic medium and preferably at a pH between 1 and 4. In order to maintain such pI-I, inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid may be employed.

The polymerization methods include aqueous solution polymerization, emulsion polymerization, suspension polymerization and water-organic solvent polymerization.

The polymerization is carried out at a temperature between C. to 80 0., preferably between 30 C. and 70 C. Below 10 C. the polymerization may hardly be carried out at economical rate, while at too high a temperature the decomposition rate of polymerization catalyst becomes too unnecessarily great to produce a desirable polymer.

The present polymerization may preferably be effected in the absence of oxygen, and therefore air in the reactor may be replaced by an inert gas such as nitrogen before the polymerization starts.

The applicable polymerization processes are batch polymerization processes, semi-continuous and continuous polymerization processes.

The features of the present invention can more fully be understood by the following non-limiting illustrating examples. Parts are by weight unless expressly stated to the contrary. The reduced viscosity of a polymer (1 is measured at a polymer concentration of 0.2 g./ 100 ml. dimethyl formamide at 35 C. and the whiteness of a polymer is calculated from reflection by a spectrophotometer assuming the value of magnesium oxide as 100.

EXAMPLE 1 In a 500 ml. glass ampoule, there were charged 1,200 parts of water, 100 parts of acrylonitrile, one part of ammonium persulfate, 5 parts of sodium bisulfite, 2 parts of sulfuric acid and a variety of oximes set forth in Table l at 5 C. After the air in the ampoule was displaced with nitrogen and the ampoule was sealed by fusion, polymerization was effected by shaking the ampoule for 4 hours in a thermostat kept at 50 C. Then, the ampoule was cooled and opened and the contents were filtered off, washed with water and dried at 50 C. to give a white polymer. The reduced viscosities and the yields of the polymer are shown in Table l. The polymer was dissolved in a 70% purified nitric acid at 0 C., regenerated in a 35% nitric acid, washed with water, dried, and subjected to dry heat treatment at 180 C. for 10 minutes and then subjected to wet heat treatment in superheated steam at 135 C. for 10 minutes. The results are shown in Table 1.

In order to compare the product with the conventional redox catalyst, polymerization was effected in the same manner as above, except that the oximes were not used.

The results are shown in Table 1.

EXAMPLE 2 In a 500 ml. glass ampoule, there were charged 1,200 parts of water, 91 parts of acrylonitrile, 8 parts of methyl acrylate, one part of sodium p-styrene sulfonate, one part of ammonium hydroxylamine-N-monosulfonate, 5 parts of sodium bisulfite, 2 parts of sulfuric acid and a variety of oximes set forth in Table 2 at 5 C. and after the air in the ampoule was displaced with nitrogen the ampoule was sealed. Polymerization was effected in the same manner as in Example 1. As in Example 1, one control experiment was run in the absence of the oxime. Then, the resulting polymers were treated in the same manner as in Example 1. The results are shown in Table 2.

EXAMPLE 3 In a 500 ml. glass ampoule, there were charged 1,200 parts of water, parts of acrylonitrile, 15 parts of vinyl acetate, 5 parts of n-butyl acrylate, one part of magnesium persulfate, 4 parts of magnesium metabisulfite, 2 parts of sulfuric acid and a variety of oximes set forth in Table 4 at 5 C. and after the air in the ampoule was displaced with nitrogen the amopule was sealed and polymerization was effected in the same manner as in Example 1. As in Example 1, a control experiment was carried out in the absence of the oxime. Then, the resulting polymers were treated in the same manner as in Example 1. The results are shown in Table 3.

EXAMPLE 4 In a 1,000 ml. glass ampoule, there were charged 1,200 parts of water, parts of acrylonitrile, one part of 2- vinylpyridine, 2 parts of methacrylic acid, 7 parts of methyl acrylate, 0.5 part of potassium persulfate, 0.5 part of sodium persulfate, 2 parts of potassium bisulfite, 2 parts of ammonium bisulfite and a variety of oximes set forth in Table 1 at 5 C. After the air in the amopule was displaced with nitrogen and the ampoule was sealed by fusion. Polymerization was carried out by shaking the ampoule in a thermostat kept at 50 C. for 4 hours. Then, the ampoule was cooled and opened and the contents were filtered off, washed with water and dried at 50 C. to give a white polymer. This polymer was dissolved in a 69% purified nitric acid at 0 C., defoamed, and extruded through a spinnerette at 0 C. into a 35 nitric acid to form yarns. These yarns were washed with water, stretched to 6 times its length in hot water at 98 C. and dried. The resulting yarns were subjected to wet heat treatment in super-heated steam at C. for 10 minutes. The results are shown in Table 4.

shown in Table 5.

EXAMPLE 5 EXAMPLE 6 Table 6. The results are shown in Table 6.

In the same manner as inExam ple 2, polymerization was carried out using 0.3 part of cyclohexanone oxime and 90 parts of acryionitrile and a variety of ethylenical- 1y unsaturated compounds as comonomer set forth in TABLE 1 A whiteness Reduced Dried after Yield viscosity polymeri- Begenerated Treated by Treated of o! zation in nitric superheated by dry Run polymer polymer (not heatacid (not steam heat heat number Oxime (parts) (parts) lux/ea) treated) heat-treated) at 135 C. at 180 C,

1 Acetaidoxirne (0. 2) 91 1.70 103 101 97 89 2 Propionaldoxime (0. 2) 92 1.71 103 101 97 90 a n-Butylnlflnrirnn (0. 2) 92 1. 71 102 100 96 87 4 i-Butylaldoxime (0. 2) 93 1.70 103 101 97 90 6 n-Pentylaldoxime (0. 2) 91 1.72 104 .102 98 91 6 iHe ylnldmrIme (0. 2) 94 1. 76 105 103 99 92 7 Acetoxime (0. 2) 92 1.76 104 102 98 90 8 Ethy1-i-buty1ketoxime.-.- (0.1) 92 1. 71 103 101 97 89 Cyclohexanone oxizne..-- (0. 1)

9 Ethylrnethyiketoximan. (0.1) 93 1. 76 102 100 94 B6 Cyclohexanone ox.ime (0. 1)

10-. Diethylketoxime (0.1) 91 1.71 102 100- 93 86 Cyclooctanone oxime..... (0.

11 Cycloheptanone oxime.-. (0. 2) 92 1.70 102 100 94 8e 12 (reference) None 88 1.66 100 97 89 TABLE 2 whiteness Reduced Dried alter Yield viscosity polymeri- Regenerated Treated by Treated of zation in nitric superheated by Run polymer polymer (not heatacid (not steam heat heat number Oxime (parts) (part8) ("law/m) treated) heat-treated) at 135 C. at 180 C 13 Acetaldoxime (0. 1) 92 1. 72 103 101 96 39 14--. (0. 2) 91 1. 76 1104 102 97 16 n-Pentylaldoxime (0. 2) 92 1. 78 102 100 83 m (0. 5) 91 1. 76 103 101 90 89 17 (1. 0) 93 1. 76 104 102 97 90 18 (4. 0) 92 1. 75 103 101 96 89 19 Methyi-n- (0. 3) 93 1. 75 103 101' 96 89 pentylketoxime. 20 ethyl-n- (0. 2) 91 1. 76 102 96 88 hexyiketoxime.

21-. Methyi-n- (0. 1) 92 1.72 103 101 96 89 heptylketoxime. Cycloundecanone oxime (0. 1)

22.. Ethyl-n-octylketoxime-.- (0. 1) 1. 76 103 101 Cyclodecanone oxime....-- (0. 1)

23 EthyI-n-nony1ketox1me.- (0. 1) 1. 78 106 101 Cyciodecanone oxlme- 1) 24 (reference) None 89 1.70 100 97 TABLE 3 whiteness Dried after Reduced polymer- Regenerated Treated by Treated Yield 01' visocisity ization in nitric superheated by dry polymer of polymer (not heatacid (not .steam heat heat Run number Oxime (parts) (parts) (mp-ls.) treated) heat-treated) .at C. at C.

25... Acetaidoxime (0. 1) 91 1. 70 102 101 .96 89 Ethylmethylketoxime (0. 1)

2e Acetoxime (o. 05) 1. vs 103 102 97 9o n-Hexylaldoxime (0.15)

27 Ethylmethyketoxime (0. 1) 94 1. 75 101 100 95 88 Ethyl-i-hexylketox'ime (0. 1)

2s Diethyllretnrima i (0. 15) 91 1. 1a 102 102 91 90 Ethyl-2-methy1buty1ketoxime (0. 5)

'29 Di-i-butylketoxime (0.1) 92 1.73 101 100 91s as Formaldoxime (0. 1)

a0 n-Butyl-i-pentylketoxime (0. 1) as 1.15 102 101 9e 89 Methy12,2-dimethylpropy1ketoxime.- (0. 1) I 31 Methyl-ndecanylketoxime (0. 1) 91 1.78 102 102 97 90 Ethyl-i-pentyiketoxime (0. 1) e 32 Di-n-propylketoxime (o. 1) 92 1. 78 103 102 97 Ethy1-3,3-d1methylpentylketoxime.. (0. 1)

33 (reference) Nnne 87 1.72 100 98 80 TABLE 4 whiteness Reduced Yarn Yield viscosity treated by oi oi superheated polymer polymer Untreated steam heat Run number Ox lme (parts) (parts) J0. yarn at 135 C.

34 Formaidoxime (0. 1) 91 1. 68 102 97 Cycloheptanone oxime..-- (0. 1)

Acetoxime... 1) 92 1. 70 101 96 Cyclooctauone oxime (0. 1)

n-Propylaidoxime (0. 1) 92 1. 71 102 97 Cycioundecanone oxime... (0. 1)

Ethyl-l-pentylketoxime. (0. 2) 91 1. 69 101 96 i-Penty (0. 2) 92 1. 70 103 97 Cycloheptanone oxime. (0. 2) 91 1. 69 102 96 40 Cyclopentanone oxime- (0. 2) 92 1. 71 103 95 41 (reference) N 85 1.65 100 85 TABLE 5 whiteness Reduced viscosity Dried after Regenerated Treated by Treated Yield oi oi polymeriaznitric superheated by dry oxidizing substance and reducing Oxime polymer polymer tion (not acid (not steam heat heat at; Run number sulioxy compound (part) (0.2 part) (parts) (1 gpJg.) heat-treated) heat-treated) at 135 0. 180 C.

42 Sodium hydroxylamine-N- (2) Acetoxime-- 92 1. 78 102 100 97 39 monosulionate. Potassium sulfite (4) 43 (reference).... Same as above None 90 1. 91 98 97 3e 79 44 Magnesium hydroxylamine-N- (2. 5) Acetoxime.. 86 1. 90 103 101 97 99 monosuitonate. Magnesium bisulflte...;....'.- (2.5)

45 (reference).... Same as above None 80 2. 01 100 98 g7 g0 46 Pei'SlllfllIlc acid (1) Acetoxime.- 91 1. 90 101 100 95 38 Sodium metabisulfite. (6)

47 (rei'erence).... Same as above None 90 1. 88 96 95 7e 48.... fligrioxylizamlne-N-monosm- (1) Acetoxime.- 95 1. 99 100 98 94 86 o 0 ac Potassium metabisulfite (3) Ammonium metabiisuifite. (3)

49 (reiereuce).... Same as above None 90 1. 76 94 91 so 71 50 HIydroxylamine-N,N-disul- (1.5) Acetoxime. 86 1. 69 101 100 95 39 o o a Sodium hyposuifite (4) 51 (reference).... Same as above... No e .2. 82 1. 56 95 92 80 52 Potassium hydroxyiamiue-N, (2) Acetoxime.. 86 1. 102 100 9g 90 N-disulionate. Potassium hyposuifite (6) 53 (reierence)..'.. Same as above.'. None 1.68 97 95 83 77 54 Sodium hydroxylamine-N, (2) Acetoxime.. 1. 91 103 101 9g 90 N-disulionate. Ammonium bisulfite.. (6)

55 (reference).... Same as above... None.....-.-. 89 1. 90 100 97 87 80 56 Magnesium hydroxyiamine- (3) Acetoxime.. 92 2. 01 104 102 99 92 N ,N-disulionate. Magnesium hyposulfite (5) 57 (reference).... Same as above None 90 2. 00 99 96 35 7g 58 Ammonium hydroxyiamiue- (2) Acetoxime.- 89 1. 8B 101 100 99 99 N ,N-disulfonate. Ammonium sulfite (8) 59 (reference).... Same as above None 87 1. 68 96 94 32 75 60 Sodium hydroxylamine-N- 2 Acetoxime-. 92 1. 98 100 99 94 90 monosulfonate. Ammonium hyposulfibe 5 61(reference)-... Same as above None 91 1. 93 95 91 30 72 62 Maguiesum hydroxylamine- 1. 5 Acetoxime. 90 1. 79 102 96 91 N-monosuliinate Magnesium sulfite 6 03 (reference) Same as above. None 86 1.64 96 95 82 75 64 Sodium chlorate 1 Acetoximm. 96 2. 14 191 100 98 90 Sodium bisulfit 65 (reference).... Same as above. None 94 2. 05 99 9B 90 6 66 otassium chlorate. 1 Acetoxime- 95 2. 20 103 101 93 91 Sodium bisulfite--- 4 67 (reference).... Same as above None 94 2.09 100 93 90 37 68 Ammonium chlorate- 1 Acetoxime- 96 2. 17 102 100 99 g Sodium bisulfite- 4 69 (reference)...- Same as above None 98 2. 07 101 93 91 5 TABLE 6 whiteness Reduced Dried after Regenerated Treated by Treated Yield of viscosity polymerizain nitric superheated by dry Oxime (0.3 polymer of polymer tion not acid (not steam heat heat Run No. Comonomer (parts) part) (part) lnpJc) heat-treated) heat-treated) at 135 C at 180 C.

70 Ethyl acrylate (10) cyggohexanone 93 1. 76 103 101 97 89 71 (reference)..- Same as above None 91 1. 70 100 97 84 79 72 Methacrylonitrile Sodium (9) Cyclohexanone 90 1. 63 103 102 98 90 methallyl-sulfonate. (1) oxime. w.

73 (reference)--. Same as above None 89 1. 61 100 98 85 80 74 Acrylamide Cyclohexanone 90 1. 59 99 98 89 83 N,N-dimethylacrylamide (5) oxime.

75 (reference)--- Same as above None 86 1. 50 96 93 79 70 76 Methylmethacrylate- Cyclohexanone 92 1.69 104 103 98 96 moms.

77 (reference)..- Same as above None 91 1. 60 101 1.00 89 85 78-- Acrylic acid (5) Cyclohexanone 92 1. 75 100 99 94 90 Methacrylic acid (5) oxime.

79 (reference).. Same as above None 90 1. 71 98 96 84 77 B0 Vinylideue chloride Cyclohexanone 91 2. 01 95 93 80 84 crime.

81 (reference).- Same as above None 90 2. 00 92 90 76 73 S2 Vinyl chloride (10) Cyclohexanone 92 1.96 96 94 87 85 83 (reference) Same as above None 91 1. 93 93 91 77 72 84 Methyl vinylether (9) Cyclohexanone 92 1. 76 100 99 92 83 Sodium allylsulionate- (1) crime.

85 (reference).-. Same as above None 91 1. 70 99 97 83 79 86 Dimethyl malonate (10) Cyclohexanone 91 l. 68 101 100 93 85 87 (reference) Same as above None 90 1. 50 100 98 89 80 What is claimed is:

1. A process for preparing a polymeric material by polymerizing (a) acrylonitrile or (b) acrylom'trile admixed with a minor amount of at least one ethylenically unsaturated compound copolymerizable therewith in an acidic aqueous medium at a temperature of from 10 C. to 80 C., using a catalyst system consisting of a redox type catalyst and at least one oxime of one of the two following general formulae:

wherein R and R are each selected from the group consisting of hydrogen and an alkyl group having 1 to 10 carbon atoms, and R represents an alkylene group having 4 to 10 carbons atoms, said redox system comprising (1) at least one oxidizing substance selected from the group consisting of persulfuric acid, the sodium, potassium, magnesium, ammonium salts thereof, hydroxylamine-N-monosulfonic acid, the sodium, potassium, magnesium, ammonium salts thereof, hydroxylamine-N,N-disulfonic acid, the sodium, potassium, magnesium, ammonium salts thereof, sodium chlorate, potassium chlorate and ammonium chlorate, and (2) at least one reducing sulfoxy compound selected from the group consisting of sulfurous acid, sodium potassium, magnesium, ammonium sulfite, sodium, potassium, magnesium, ammonium, hyposulfite, sodium, potassium, magnesium, ammonium bisulfite and sodium, potassium, magnesium, ammonium metabisulfite.

2. A process as claimed in claim 1, wherein the polymerization is efl'ected in an aqueous medium of pH 1 to 4.

3. A process as claimed in claim 1, wherein the ethylenically unsaturated compound copolymerizable with acrylonitrile is selected from the group consisting of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylamide, methacrylamide, N,N-dimethyl acrylamide, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, methyl vinyl ether, dimethyl maloate, allyl sulfonic acid, methallyl sulfonic acid, p-styrene sulfonic acid, the sodium, potassium, ammonium salts of allyl sulfonic acid, methallyl sulfonic acid and p-styrene sulfonic acid.

4. A process as claimed in claim 3, wherein said ethylem'cally unsaturated compound is employed in an amount of 0.01 to 40 mole percent based on the acrylonitrile.

5. A process as claimed in claim 3, wherein said ethylenically unsaturated compound is employed in an amount of 0.01 to 15 mole percent of the acrylonitrile.

6. A process as claimed in claim 1, wherein the oxime is selected from the group consisting of formaldoxime, acetaldoxime, propionaldoxime, n-butylaldoxime, i-butylaldoxime, n-pentylaldoxime, i-pentylaldoxime, n-hexylaldoxime, i-hexylaldoxime, acetoxime, ethylmethylketoxime, ethyl-i-butyl-ketoxime, diethylketoxime, di i butylketoxime, di-n-propylketoxime, ethyl i pentylketoxime, ethyl-i-hexylketoxime, ethyl-n-octylketoxime, ethyl-n-nonylketoxime, ethyl-2-methylbutylketoxime, methyl-n-pentylketoxime, methyl-n-hexylketoxime, methyl n heptylketoxime, methyl n decanylkctoxime, methyl 2,2 dimethylpropylketoxime, ethyl 3,3 dimethylpentylketoxime, n-butyl-i-pentylketoxime, cyclopentanone oxime, cyclohexanone oxime, cycloheptanone oxime, cyclooctanone oxime, cyclodecanone oxime and cycloundecanone oxime.

7. A process as claimed in claim 6, wherein said oxime is employed in an amount of about 5 to 100 percent by Weight of the oxidizing substance.

8. A process as claimed in claim 1, wherein said oxidizing substance is employed in an amount of about 0.1 to 10 percent by weight of the acrylonitrile or the acrylonitrile admixed with a minor amount of at least one ethylenically unsaturated compound, and the reducing sulfoxy compound is employed in an amount of upto 30 percent by weight of the acrylonitrile or the acrylonitrile admixed with a minor amount of at least one ethylenically unsaturated compound.

9. A process as claimed in claim 1, wherein the polymerization is effected at a temperature of from 30 C. to 70 C.

1 1 1 2 10. A process as claimed in claim 1, wherein the acrylo- FOREIGN PATENTS nitrile or the acrylonitrile admixed with a minor amount 8 844 1962 Japan 5 N of at least one ethylenically unsaturated compound and n water are present in a Weight ratio of about 1:1 to 1:30. JOSEPH L SCHOFER, Primary E i References Cited 5 I. KIGHT III, Assistant Examiner UNITED STATES PATENTS CL 3,202,641 8/1965 Nakaiima et a1 26079.7, 85.5 R, ES, AM, XA, N, 85.7, 86.1 N, 88.7

3,607,835 9/1971 Paleologo et a1. 26063 N R,F 

